Sample channel for a sensor for measuring fluid properties

Abstract

A downhole tool includes a body that includes a sample port through which a sample fluid can be drawn into the downhole tool and a sample channel passing through the body in fluid communication with the sample port and through which the sample fluid travels. The sample channel includes a sample chamber having an inlet and an outlet located along the sample channel, the sample chamber including three cylindrical chambers including a middle resonator cavity surrounded by two outer resonator cavities, one of the two outer resonator cavities including a sensor inlet for receiving a sensor and allowing it to fluidly contact the sample fluid as it travels through the sample channel.

What is claimed is: 
     
       1. A downhole tool including a body comprising:
 a sample port through which a sample fluid can be drawn into the downhole tool; 
 a sample channel passing through the body in fluid communication with the sample port and through which the sample fluid travels, the sample channel including:
 a sample chamber having an inlet and an outlet located along the sample channel, the sample chamber including three cylindrical chambers including a middle resonator cavity surrounded by two outer resonator cavities, one of the two outer resonator cavities including a sensor inlet for receiving a sensor and allowing it to fluidly contact the sample fluid as it travels through the sample channel. 
 
 
     
     
       2. The downhole tool of  claim 1 , wherein middle and outer resonator cavities are concentric. 
     
     
       3. The downhole tool of  claim 1 , wherein the inlet and the outlet are both formed in the middle resonator cavity. 
     
     
       4. The downhole tool of  claim 3 , wherein the inlet and outlet are staggered relative to one another. 
     
     
       5. The downhole tool of  claim 1 , further comprising:
 a sensor disposed in the sensor inlet. 
 
     
     
       6. The downhole tool of  claim 5 , wherein the sensor includes a diaphragm and the diaphragm is located such that it is in one of the outer sample chambers and the middle chamber. 
     
     
       7. The downhole tool of  claim 6 , wherein the diaphragm is not in the other of the outer sample chambers. 
     
     
       8. The downhole tool of  claim 6 , wherein the volume within the one of the sample chambers not occupied by the diaphragm defines a baffle gap. 
     
     
       9. The downhole tool of  claim 1 , wherein the sensor includes:
 a preload adapter having a sleeve portion and an end; 
 a housing including a seating portion and a shaft portion that extends from the seating portion; and 
 a piezoelectric element contained completely within a chamber that is at least partially defined by the sleeve portion and shaft portion; 
 wherein the diaphragm is coupled to an external side of the end such that motion of the piezoelectric element causes motion of the diaphragm. 
 
     
     
       10. The downhole tool of  claim 9 , wherein the sensor inlet includes an inner shelf that contacts the preload adapter. 
     
     
       11. The downhole tool of  claim 9 , wherein the sensor further includes:
 a retaining mechanism on an opposite side of the seating portion from the shaft portion and including mating features configured to mate with the body; and 
 a preload spring disposed between the retaining mechanism and the seating portion; 
 wherein mating the retaining mechanism with the body causes the preload spring to urge the preload adapter toward the inner shelf and to create a compressive force between them. 
 
     
     
       12. The instrument of  claim 9 , further comprising:
 a voltage supply coupled to the piezoelectric element. 
 
     
     
       13. A method of evaluating a sample fluid, the method comprising:
 drawing a fluid from a downhole location into a sample chamber in a downhole tool; 
 passing the fluid through a sample chamber, the sample chamber including an inlet and an outlet located along the sample channel, the sample chamber including three cylindrical chambers including a middle resonator cavity surrounded by two outer resonator cavities, one of the two outer resonator cavities including a sensor inlet for receiving a sensor and allowing it to fluidly contact the sample fluid as it travels through the sample channel; and 
 evaluating the sample fluid with the sensor as it passes through the sample chamber. 
 
     
     
       14. The method of  claim 13 , wherein evaluating includes providing a voltage that causes an piezoelectric element within the sensor to cause a diaphragm of the sensor to move. 
     
     
       15. The method of  claim 13 , further comprising:
 disposing the sensor in the sensor inlet.